BTS3256D - Infineon Technologies

Automotive

Datasheet

Rev. 1.0, 2009-05-05

BTS3256D

10 mΩ smart power single channel low side switch with restart and variable slew rate

HITFET™

Smart Low Side Power Switch

Datasheet 2 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Table of Contents

Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 BTS 3256D Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2.1 Voltage and current naming definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3 Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.1 Pin Assignment BTS 3256D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

3.2 Pin Definitions and Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4 General Product Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4.1 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4.2 Functional Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.3 Thermal Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

5 Supply and Input Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5.1 Supply Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5.1.1 Under Voltage Lock Out / Power On Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5.2 Input Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5.3 Electrical Characteristics - Supply and Input Stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6Power Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

6.1 Output On-state Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

6.2 Output Timings and Slopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

6.3 Inductive Output Clamp . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

6.4 Electrical Characteristics - Power Stage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

7 Control and Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

7.1 Readout of Fault Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

7.2 Adjustable Slew Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

7.3 Electrical Characteristics - Diagnostic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

8 Protection Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

8.1 Thermal Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

8.2 Over Voltage Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

8.3 Short Circuit Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

8.4 Electrical Characteristics - Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

9 Application Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

9.1 Dimensioning of serial Resistor at IN pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

9.2 Further Application Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

10 Package Outlines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

11 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Table of Contents

Type Package

BTS 3256D PG-TO-252-5-11

Datasheet 3 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

BTS3256D

BTS 3256D

PG-TO-252-5-11

1Overview

The BTS 3256D is a single channel low-side power switch in

PG-TO-252-5-11 package providing embedded protective functions.

This HITFET™ is designed for automotive and industrial

applications with outstanding protection and control features.

The power transistor is a N-channel vertical power MOSFET.

The device is controlled by a chip in Smart Power Technology.

Basic Features

• Slew rate control by dedicated pin enabling EMC optimized switching or PWM operation

• Max. switching Frequency 12kHz

• Clear detection of digital fault signal also during fast PWM operation due to restart delay time

• Thermal and overload protection with time controlled auto restart behavior

• Time and Power limited active current limitation

• Minimum RDS(on) achieved with 3.3V or 5V logic input

• Electrostatic discharge protection (ESD)

• Very low leakage current

• Green Product (RoHS compliant)

• AEC (Automotive Electronics Council) Stress Test Qualification

Table 1 Basic Electrical Data

Operating voltage VSOP 5.5 V.... 30 V

Over voltage protection VD (AZ) 40 V

Maximum ON State resistance at Tj = 150°C RDS(ON,max) 20 mΩ

Typical ON State resistance at Tj = 25°C RDS(ON,typ) 10 mΩ

Nominal load current ID(nom) 7.5 A

Minimum current limitation ID(lim) 42 A

Datasheet 4 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Overview

Digital Diagnostic Features

• Over temperature

• Over load

•Short circuit

• Clear detection due to a restart delay time

Protection Functions

• Enhanced short circuit protection with time and power limited active current limitation

• Under voltage lock out

• Over temperature with time and temperature controlled auto restart

• Over load with power and time controlled auto restart

• ESD protection

Application

• All types of resistive, inductive and capacitive loads

• Suitable for loads with inrush current, such as motors, coils, solenoids or lamps

• Suitable for EMC optimized switching in slow operation mode

• Suitable for higher speed PWM controlled loads in fast operation mode

• Replacement of electromechanical relays, fuses and discrete circuits

• Micro controller compatible low side power switch with digital feedback for 12V loads

Detailed Description

The BTS 3256D is an autorestart single channel low-side power switch in PG-TO-252-5-11 package providing

embedded protective functions. The device is able to switch all kind of resistive, inductive and capacitive loads.

The ESD protection of the VS and IN/Fault pin is referenced to GND.

The BTS 3256D is supplied by the VS Pin. This Pin should be connected to a reverse protected battery line. The

supply voltage is monitored by the under voltage lock out circuit. The Gate driving unit allows the device to operate

in the lowest ohmic range independent of the input signal level, 3.3 V or 5 V . For slow PWM application the device

offers smooth turn-on and off due to the embedded edge shaping function, to reduce EMC noise. Furthermore the

SRP pin can be used to customize the slew rate of the device in a wide range.

The Device is designed for driving automotive loads like motors,valves, coils or bulbs in continous or PWM mode.

The over voltage protection is for protection during load-dump or inductive turn off conditions. The power MOSFET

is limiting the Drain-Source voltage to a specified level. This function is available even without any supply.

The over temperature protection prevents the device from overheating due to overload and/or bad cooling

conditions. In order to reduce the device stress the edge shaping is disabled during thermal shutdown. After

thermal shutdown the device stays off for the specified restart delay time to enable a clear feedback readout on

the microcontroller. After this time the device follows the IN signal state.

At high dynamic overload conditions, such as short circuit, the device will either turn off immediately due to the

implemented over power limitation, or limit the current for a specified time and then switch off for the restart delay

time. Shutdown of the device is triggered if the power dissipation during limitation is above the over power

threshold. The short circuit shutdown is a timed restart function. The device will stay off for the specified time and

afterwards follow the IN signal state. In order to reduce the device stress the edge shaping is disabled during

protective turn off.

Datasheet 5 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

BTS 3256D Block Diagram

2 BTS 3256D Block Diagram

Figure 1 Block Diagram for the BTS3256D

2.1 Voltage and current naming definition

Following figure shows all the terms used in this datasheet, with associated convention for positive values.

Figure 2 Terms

Drain

GND

Gate

Driving

Unit

Over-

voltage

Protection

ESD

protection

IN / Fault

Over-

temperature

Protection

Overload

Protection

SRP

Short

circuit

Protection

BlockDiagram.emf

Under

voltage

lockout

Slew rate

control

Terms.emf

VIN

GND

I GND

Drain

Vbb

IN / Fault

VSID

IIN

Vbb

GND

SRP

VSR P

Datasheet 6 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Pin Configuration

3 Pin Configuration

3.1 Pin Assignment BTS 3256D

Figure 3 Pin Configuration

3.2 Pin Definitions and Functions

Pin Symbol Function

1VSSupply Voltage;

Connected to Battery Voltage with Reverse protection Diode and Filter against EMC

2IN Control Input and Status Feedback; Digital input 3.3 V or 5 V logic.

3, Tab Drain Drain output;

Protected low side power output channel, usually connected via load to battery

4SRP Slew Rate Preset; Used to define slew rate, see Chapter 7.2 for details

5GND Ground; Power ground, pin connection needs to carry the load current from Drain

Drain Drain

(top view )

GND

6 (Tab)

SRP

PinConfiguration.emf

Datasheet 7 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

General Product Characteristics

4 General Product Characteristics

4.1 Absolute Maximum Ratings

Note: Stresses above the ones listed here may cause permanent damage to the device. Exposure to absolute

maximum rating conditions for extended periods may affect device reliability.

Note: Integrated protection functions are designed to prevent IC destruction under fault conditions described in the

data sheet. Fault conditions are considered as “outside” normal operating range. Protection functions are

not designed for continuous repetitive operation.

Absolute Maximum Ratings 1)

Tj = -40 °C to +150 °C

All voltages with respect to ground, positive current flowing into pin (unless otherwise specified)

1) Not subject to production test, specified by design.

Pos. Parameter Symbol Limit Values Unit Conditions

Min. Max.

Voltages

4.1.1 Supply voltage VS-0.3 30 V –

4.1.2 Supply voltage during active clamping VS(pulse) -0.3 452)

2) Not for DC operation, only for short pulse (i.e. loaddump) for a total of 100 h in full device life.

V–

4.1.3 Drain voltage VD-0.3 403)

3) Active clamped.

V–

4.1.4 Drain voltage for short circuit protection VD(SC) 030V

4) The Device can not be switched on if VD > VD(SC)

4.1.5 Logic input voltage VIN -0.3 5.5 V –

4.1.6 Slew Rate Preset maximum voltages VSRP -0.3 5.5 V 5)

5) SRP Pin is driven by an internal current source, so active driving from outside is not required,it may affect lifetime and could

cause parameter shifts outside the range given in datasheet

Energies

4.1.7 Unclamped single pulse inductive

energy

EAS 00.3JID = 22 A;

Vbb = 30 V

Temperatures

4.1.8 Junction Temperature Tj-40 150 °C–

4.1.9 Storage Temperature Tstg -55 150 °C–

ESD Susceptibility

4.1.10 ESD Resistivity VESD kV HBM6)

6) ESD susceptibility, HBM according to EIA/JESD 22-A114B, section4

on input pins (IN,SRP,VS) IN -4 4

on Drain and GND pins OUT -8 8

Datasheet 8 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

General Product Characteristics

4.2 Functional Range

Note: Within the functional range the IC operates as described in the circuit description. The electrical

characteristics are specified within the conditions given in the related electrical characteristics table.

4.3 Thermal Resistance

Pos. Parameter Symbol Limit Values Unit Conditions

Min. Max.

4.2.1 Supply Voltage VS5.5 30 V –

4.2.2 Supply current in on IS–3mA–

Pos. Parameter Symbol Limit Values Unit Conditions

Min. Typ. Max.

4.3.1 Junction to Case1)

1) Not subject to production test, specified by design

RthjC – 0.9 1.1 K/W –

4.3.2 Junction to ambient1) RthjA – 80 – K/W @min. footprint

– 45 – K/W @ 6 cm² cooling

area, see Figure 4

Datasheet 9 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

General Product Characteristics

Figure 4 Typical transient thermal impedance

ZthJA = f(tp) , Pulse D = tp/T, Ta = 25 °C

Device on 50 mm × 50 mm × 1.5 mm epoxy PCB FR4 with 6 cm2 (one layer, 70 µm thick) copper area for

drain connection. PCB mounted vertical without blown air.

ZthJA

0.1

K/W

Zth.emf

0.2

0.1

0.5

Single pulse

0.01

0.02

0.05

100

10-3 10-2 10-1

10-6 10-5 10-4 11010

2103

Datasheet 10 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Supply and Input Stage

5 Supply and Input Stage

5.1 Supply Circuit

The Supply pin VS is protected against ESD pulses as shown in Figure 5.

Due to an internal voltage regulator the device can be supplied from a reverse polarity protected battery line.

Figure 5 Supply Circuit

5.1.1 Under Voltage Lock Out / Power On Reset

In order to ensure a stable device behavior under all allowed conditions the Supply voltage VS is monitored by the

under voltage lock out circuit. All device functions are only given for supply voltages above under voltage lockout.

There is no failure feedback for VS<VSUVON.

Figure 6 Under Voltage Lock Out

5.2 Input Circuit

Figure 7 shows the input circuit of the BTS 3256D. It’s ensured that the device switches off in case of open input

pin. A Zener structure protects the input circuit against ESD pulses. As the BTS 3256D has a supply pin, the

operation of the power MOS can be maintained regardless of the voltage on the IN pin, therefore a digital status

feedback down to logic low is realized. For readout of the fault information, please refer to Diagnosis “Readout of

Fault Information” on Page 20.

Supply .emf

5.5 V .. 30 V

GND

Regulator

BTS3256 D

SUVON

SUVOFF

functional

off

Device

UVLO.emf

Datasheet 11 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Supply and Input Stage

Figure 7 Input Circuit

input.em

GND

IN/Fault

1.0mA

3.0mA

20µA

100µA

Datasheet 12 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Supply and Input Stage

5.3 Electrical Characteristics - Supply and Input Stages

VS = 5.5 V to 30 V, Tj = -40 °C to +150 °C

All voltages with respect to ground, positive current flowing into pin (unless otherwise specified)

Pos. Parameter Symbol Limit Values Unit Conditions

Min. Typ. Max.

Under Voltage Lockout

5.3.1 UV-switch-on voltage VSUVON ––5.6V–

5.3.2 UV-switch-off voltage VSUVOFF 4.0 – 5.5 V –

5.3.3 UV-switch-off hysteresis VSUVHY –0.2–VVSUVON - VSUVOFF

Digital Input / Fault Feedback

5.3.4 Low level voltage VINL -0.3 – 0.8 V –

5.3.5 High level voltage VINH 2.0 – 5.5 V –

5.3.6 Input pull down current IIN 20 50 100 µAVIN = 5.3 V;

no fault condition

5.3.7 Input pull down current in Fault IIN-Fault 123mAVIN = 5.3 V; all fault

conditions

Datasheet 13 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Power Stage

6 Power Stage

The power stage is built by a N-channel vertical power MOSFET (DMOS).

6.1 Output On-state Resistance

The on-state resistance depends on the junction temperature TJ. Figure 8 shows this dependence for the typical

on-state resistance RDS(on).

Figure 8 Typical On-State Resistance RDSon = f(TJ), VS = 10 V, VIN = high

Figure 9 Typical On-State Resistance RDSon = f(VS), VIN = high, Tambient = 25 °C

-50 -25 0 25 50 75 100 125 150 175

typ.

rdson_Tj.emf

T [ °C ]

RDS(on) [ mΩ ]

0102030

DS(on)

[ mΩ ]

[ V ]

rdson_Vs.emf

typ.

Datasheet 14 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Power Stage

6.2 Output Timings and Slopes

A high signal on the input pin causes the power MOSFET to switch on with a dedicated slope which is optimized

for low EMC emission. Figure 10 shows the timing definition.

Figure 10 Definition of Power Output Timing for Resistive Load

In order to minimize the emission during switching, the BTS 3256D limits the slopes during turn on and off at slow

slew rate settings. For best performance of the edge shaping, the supply pin VS should be connected to battery

voltage. For supply voltages other than nominal battery, the edge shaping can differ from the Values in the

electrical characteristics table below.

6.3 Inductive Output Clamp

When switching off inductive loads with low-side switches, the Drain Source voltage VD rises above battery

potential, because the inductance intends to continue driving the current.

The BTS 3256D is equipped with a voltage clamp mechanism that keeps the Drain-Source voltage VD at a certain

level. See Figure 11 for more details.

Figure 11 Output Clamp

Low

High

ton toff t

Vbb

OutputTiming.emt

tond

10 %

90 %

toffd

|dv/dt| s haping

|dv/ dt| s haping

|dv/dt|on |dv/dt|off

80 %

20 % |dv/dt| s haping

output_clamp_curcuit.emf

GND

Drain

Datasheet 15 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Power Stage

Figure 12 Switching off an inductive Load

While demagnetization of inductive loads, energy has to be dissipated in the BTS 3256D. This energy can be

calculated with following equation:

Following equation simplifies under assumption of RL = 0

Figure 13 shows the inductance / current combination the BTS 3256D can handle.

For maximum single avalanche energy please also refer to EAS value in “Energies” on Page 7.

Low

High

Von

DAZ

Overtemperature or

shor t cir cuit detected

inductive_output_clamp.emf

D(AZ)

Vbb V–D(AZ)

-------------------------------- ln⋅1RLIL

⋅

Vbb V–DAZ()

---------------------------------–







------

⋅⋅=

---LIL

21Vbb

Vbb V–D(AZ)

--------------------------------–







⋅=

Datasheet 16 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Power Stage

Figure 13 Maximum allowed inductance values for single switch off (EAS)

(IL), Tj,start= 150 °C, Vbb=30V, RL= 0 Ω

0,01

0,10

1,00

10,00

[ A ]

L [ mH ]

Max.

EAS .emf

Datasheet 17 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Power Stage

6.4 Electrical Characteristics - Power Stage

VS = 5.5 V to 30 V, Tj = -40 °C to +150 °C

All voltages with respect to ground, positive current flowing into pin (unless otherwise specified)

Pos. Parameter Symbol Limit Values Unit Conditions

Min. Typ. Max.

Power Supply

6.4.1 On-state resistance RDS(on) –10–mΩTJ = 25 °C;

ID = 20 A;

VIN = high

VS = 10 V

–1620mΩTJ = 150 °C;

ID = 20 A;

VIN = high

VS = 10 V

6.4.2 Nominal load current1) ID(nom) 7.5 8.7 – A TJ < 150 °C;

TA 85 °C SMD2);

VIN = high;

VS ≥ 10 V;

VDS = 0.5 V

6.4.3 ISO load current1) ID(ISO) 31 33 – A TJ < 150 °C;

TC = 85 °C;

VIN = high

VS ≥ 10 V;

VDS = 0.5 V;

6.4.4 Off state drain current IDSS –612µAVD = 32 V;

VIN = low

6.4.5 – 1 2 µA1) TJ = 85 °C;

VD = 13.5 V;

VIN = low

Dynamic Characteristics

6.4.6 power up settling time tinit –1025µsVs > 6V

first rising edge on

IN pin.

Timings with fastest slew rate setting

6.4.7 Turn-on delay tond_fast –410µsRL = 2.2 Ω;

RSRP = OPEN;

Vbb = VS = 13.5 V;

see Figure 10

6.4.8 Turn-on time ton_fast –1122µsRL = 2.2 Ω;

RSRP = OPEN;

Vbb = VS = 13.5 V;

see Figure 10

6.4.9 Turn-off delay toffd_fast 41015µsRL = 2.2 Ω;

RSRP = OPEN;

Vbb = VS = 13.5 V;

see Figure 10

Datasheet 18 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Power Stage

6.4.10 Turn-off time toff_fast 91624µsRL = 2.2 Ω;

RSRP = OPEN;

Vbb = VS = 13.5 V;

see Figure 10

6.4.11 Slew rate on -dVD/dton_fast 1.2 2.2 3.8 V/µsRL = 2.2 Ω;

RSRP = OPEN;

Vbb = VS = 13.5 V;

see Figure 10

6.4.12 Slew rate off dVD/dtoff_fast 1.2 2.2 3.8 V/µsRL = 2.2 Ω;

RSRP = OPEN;

Vbb = VS = 13.5 V;

see Figure 10

6.4.13 Slew rate during edge

shaping

|dV/dt|shaping_fast –0.66– V/µs1) RL = 2.2 Ω

RSRP = OPEN;

Vbb = VS = 13.5 V;

see Figure 10

Timings with slowest slew rate setting

6.4.14 Turn-on delay tond_slow –2260µsRL = 2.2 Ω;

RSRP = GND;

Vbb = VS = 13.5 V

see Figure 10

6.4.15 Turn-on time ton_slow –85200µsRL = 2.2 Ω;

RSRP = GND;

Vbb = VS = 13.5 V

see Figure 10

6.4.16 Turn-off delay toffd_slow –75110µsRL = 2.2 Ω;

RSRP = GND;

Vbb = VS = 13.5 V

see Figure 10

6.4.17 Turn-off time toff_slow 40 150 220 µsRL = 2.2 Ω;

RSRP = GND;

Vbb = VS = 13.5 V

see Figure 10

VS = 5.5 V to 30 V, Tj = -40 °C to +150 °C

All voltages with respect to ground, positive current flowing into pin (unless otherwise specified)

Pos. Parameter Symbol Limit Values Unit Conditions

Min. Typ. Max.

Datasheet 19 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Power Stage

6.4.18 Slew rate on -dVD/dton_slow 0.08 0.2 0.6 V/µsRL = 2.2 Ω;

RSRP = GND;

Vbb = VS = 13.5 V

see Figure 10

6.4.19 Slew rate off dVD/dtoff_slow 0.08 0.2 0.6 V/µsRL = 2.2 Ω;

RSRP = GND;

Vbb = VS = 13.5 V

see Figure 10

6.4.20 Slew rate during edge

shaping

|dV/dt|shaping_slow – 0.088 – V/µs1) RL = 2.2 Ω;

RSRP = GND;

Vbb = VS = 13.5 V

see Figure 10

Inverse Diode

6.4.21 Inverse Diode forward

voltage

VD-0.3 -1.0 -1.5 V ID = -12 A;

VS = 0 V;

VIN = 0.0 V

1) Not subject to production test, specified by Design.

2) Device mounted according to EIA/JESD 52_2, FR4, 50 × 50 × 1.5 mm; 35µ Cu, 5µ Sn; 6 cm2 .

PCB mounted without blown air

VS = 5.5 V to 30 V, Tj = -40 °C to +150 °C

All voltages with respect to ground, positive current flowing into pin (unless otherwise specified)

Pos. Parameter Symbol Limit Values Unit Conditions

Min. Typ. Max.

Datasheet 20 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Control and Diagnosis

7 Control and Diagnosis

The BTS3256D provides digital fault feedback on the IN pin without the need of an ADC.

Additonally the device features an adjustable slew rate via the SRP pin.

7.1 Readout of Fault Information

The BTS 3256D provides digital status information via an increased current on the IN / Fault pin.

The voltage on this pin is pulled down to logic low when a fitting serial resistor is used. An example for the required

circuitry is shown in Figure 14. The increased current IIN(fault) is one order of magnitude above the normal operation

current IIN.

A 3k3 for a 3.3V µC or 5k6 for a 5V µC is recommended.

For detailed calculation please refer to “Dimensioning of serial Resistor at IN pin” on Page 26.

Figure 14 Readout of feedback information and XOR logic in micro

7.2 Adjustable Slew Rate

In order to optimize electromagnitic emission, the switching speed of the MOSFET can be adjusted by connecting

an external resistor between SRP pin and GND. This allows for balancing between electromagnetic emissions and

power dissipation. RSRP-min represents the minimum slew rate Slew ratemin and RSRP-max represents the maximum

slew rate Slew ratemax.

A short to GND causes the minimum slew rate Slew ratemin.

Open pin condition causes the maximum Slew rate Slew ratemax.

Figure 15 shows the relation between the resistor value and the slew rate of BTS 3256D.

IN/Fault

BTS3256

Micro

contr oller

GND

Fault

Fault_readout.emf

Datasheet 21 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Control and Diagnosis

7.3 Electrical Characteristics - Diagnostic

Figure 15 Typical relation between slew rate and resistor values used on RSRP (Vbat=13.5V)

VS = 5.5 V to 30 V, Tj = -40 °C to +150 °C

All voltages with respect to ground, positive current flowing into pin (unless otherwise specified)

Pos. Parameter Symbol Limit Values Unit Conditions

Min. Typ. Max.

Slew rate control

7.3.1 Slew ratemin Slew

ratemin

0.08 0.2 0.6 V/µs RSRP = 0 Ohm

VS = 13.5 V;

ohmic load

7.3.2 Slew rate15k Slew

rate15k

0.2 0.6 – V/µs RSRP = 15 kOhm

VS = 13.5 V;

ohmic load

7.3.3 Slew rate30k Slew

rate30k

0.7 1.45 – V/µs RSRP = 30 kOhm

VS = 13.5 V;

ohmic load

7.3.4 Slew ratemax Slew

ratemax

1.2 2.2 3.8 V/µs SRP pin open

VS = 13.5 V;

ohmic load

0,5

1,5

2,5

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

Slew rate [ V/µs ]

SRP

[ kΩ ]

Slewrate.emf

Datasheet 22 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Protection Functions

8 Protection Functions

The device provides embedded protection functions against over temperature, over load and short circuit.

Note: Integrated protection functions are designed to prevent IC destruction under fault conditions described in the

data sheet. Fault conditions are considered as “outside” normal operation.

8.1 Thermal Protection

The device is protected against over temperature resulting from overload and / or bad cooling conditions.

The BTS 3256D has a thermal restart function. When overheating occurs, the device switches off for the restart

delay time trestart. After this time the device restarts if the temperature is below threshold and the IN has logic high

level. The fault feedback is activated during over temperature situation. See Figure 16 for the restart behavior.

The diagram naming refers to Figure 14.

Figure 16 Status Feedback via Input Current at Over temperature

8.2 Over Voltage Protection

The BTS 3256D is equipped with a voltage clamp mechanism that keeps the Drain-Source voltage VD at a certain

level. This stage is also used for inductive clamping.

See “Inductive Output Clamp” on Page 14 for details.

Low

High

Therm al shutdown

low

high

JSD

INnom

IN fa u lt

∆T

JSD

After delay time , IN is high

Over temperature is gone

Don’t care

thermal_fault_autorestart.emf

restart

Datasheet 23 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Protection Functions

8.3 Short Circuit Protection

The condition short circuit is an overload condition of the device.

In a short circuit condition, the resulting dI / dt is a function of the short circuit resistance. The BTS3256D

incorporates 2 shut down strategies for maximum robustness in the presence of short circuits:

- immediate shut down in the case of low ohmic shorts by power detection exceeding Pmax

- over temperature shut down in the case of an overload condition

The additional feature of this device is a limitation of the load current to Ilim for a maximum time of tlim.

If the condition is normalized in a shorter time than tlim, the device stays on, if not the device switch off for trestart

and tries to restart in case the IN pin is still high.

From first switch off the fault feedback will be activated during trestart and continues until the IN pin goes low or

normal condition is reached.

Figure 18 shows the behavior mentioned above. In this example first a shorted load occurs which causes the

device to limit the current. The device stays on, because the load current returns to normal condition before trestart.

In the second switch on, the short circuit is permanent and the device switches OFF after maximum limiting time,

stays OFF for the blanking time regardless of the input pin condition and then stays OFF according to the IN pin

low condition.

The definitions of voltages and currents are in respect to Figure 14. The behavior of VDI also depends on RIN.

Figure 17 Typical Power limitation behavior IDS / VDS

0102030

ID[ A ]

VDrain [ V ]

Power_limitation.emf

Safe operation area

Protective Shut Down

Datasheet 24 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Protection Functions

Figure 18 Short Circuit during On State, Typical Behavior for Ohmic Loads

The case when the device switches on into an existing short circuit - Short circuit type 1- is shown in Figure 17.

The test setup for short circuit characterization is shown in Figure 19. The BTS 3256D is a low side switch.

Therefore it can be assumed that the micro controller and device GND connection have a low impedance. All

impedance in the short circuit path is merged in the short circuit resistance RSC and short circuit inductance LSC.

Figure 19 Test Setup for Short Circuit Characterization Test

low

high

Inrush

Overload

low

high

lim

INnom

IN fa u l t

Dnom

lim

Don’t care

Overload

situation

overload

shut off

protection_behaviour.emf

restart

lim

GND

Drain

BTS3 256

GND

Vbb

RSC LSC

Control circuit

Vcc

SRP

short_circuit_schematic.emf

RSRP

Datasheet 25 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Protection Functions

8.4 Electrical Characteristics - Protection

VS = 5.5 V to 30 V, Tj = -40 °C to +150 °C

All voltages with respect to ground, positive current flowing into pin (unless otherwise specified)

Pos. Parameter Symbol Limit Values Unit Conditions

Min. Typ. Max.

Thermal Protection

8.4.1 Thermal shut down junction

temperature

TJSD 150 1751)

1) Not subject to production test, specified by design.

–°C–

8.4.2 Thermal hysteresis ∆TJSD –10–K

Over Voltage Protection

8.4.3 Drain source clamp voltage VD(AZ) 40 44 - V ID = 10 mA;

VS = 0.0 V;

VIN = 0.0 V

– 4549VID = 8 A;

VS = 0.0 V;

VIN = 0.0 V

Short Circuit Protection

8.4.4 current limitation level ID(lim) 42 55 72 A ohmic load

8.4.5 max. power switch OFF threshold Pmax 300 400 650 W –

8.4.6 max. time for current limitation

before shut OFF

tlim 3.5 5 6.5 ms 2)

resistive load

2) In case of inductive loads the device needs to increase the VDS voltage during current limitation.

This can trigger the over Power protection switch off earlier as tlim.

8.4.7 restart delay time trestart 50 70 100 ms –

Datasheet 26 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Application Information

9 Application Information

Note: The following information is given as a hint for the implementation of the device only and shall not be

regarded as a description or warranty of a certain functionality, condition or quality of the device.

9.1 Dimensioning of serial Resistor at IN pin

In order to use the digital feedback function of the device, there must be a serial resistor used between the IN pin

and the driver (micro controller).

To calculate this serial resistor on the input pin, three device conditions and of course the driver (micro controller)

abilities need to be taken into account.

Figure 20 shows the circuit used for reading out the digital status.

Figure 20 Circuitry to readout fault information

Note: This is a very simplified example of an application circuit. The function must be verified in the real application.

Conditions to be meet by the circuitry:

During normal operation VIN must be higher than VINH,min to switch ON.

During fault condition the max. capability of the driver (micro controller) must not be exceeded and the logic low

level at DI must be ensured by a voltage drop over the serial resistor RIN while the device fault current is flowing.

Conditions in formulas:

•µCoutput current,min > µCHIGH,max / RIN > IINFault_min

with µCoutput current,min referring to the µC maximum output current capability

with µCHIGH,max referring to the maximal high output voltage of the µC driving stage

This condition is valid during status feedback operation mode

•VIN = µCHIGH,min - (RIN * IIN,max) > VINH,min

with µCHIGH,min referring to the minimal high output voltage of the µC driving stage

This condition is valid during normal operation mode

IN/Fault

1.0mA

3.0mA

20µA

100µA

Faul t i nfor mation

Micr ocontr oll er

BTS3256

RIN

GND

Fault_R1dim.emf

SRP

Datasheet 27 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Application Information

•µCHIGH,max - (RIN * IIN-Fault,min) < µC(DI)L,max

with µC(DI)L,max referring to the maximum logic low voltage of the µC input stage

The maximum current is either defined by the BTS 3256D or the µC driving stage

This condition is valid during status feedback operation mode

Out of this conditions the minimum and maximum resistor values can be calculated.

For a typical 5V micro controller with output current capability in the 3 mA range,

a resistor range from 7.5 kΩ down to 4.5 kΩ can be used.

For a typical 3.3V micro controller a range from 4.6 kΩ to 2.5 kΩ is suitable.

9.2 Further Application Information

• For further information you may contact http://www.infineon.com/hitfet

Datasheet 28 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Package Outlines

10 Package Outlines

Figure 21 PG-TO-252-5-11 (Plastic Green Thin Outline Package)

Green Product (RoHS compliant)

To meet the world-wide customer requirements for environmentally friendly products and to be compliant with

government regulations the device is available as a green product. Green products are RoHS-Compliant (i.e

Pb-free finish on leads and suitable for Pb-free soldering according to IPC/JEDEC J-STD-020).

GPT09161

5.4±0.1

-0.10

6.5+0.15

±0.5

9.9

6.22-0.2

1±0.1

±0.15

0.8

0.15 max

±0.1

per side 5x0.6

1.14

4.56

+0.08

-0.04

0.9

2.3-0.10

+0.05

0.51 min

±0.1

+0.08

-0.04

0.5

0...0.15

A0.25 M

0.1

All metal surfaces tin plated, except area of cut.

(4.17)

You can find all of our packages, sorts of packing and others in our

Infineon Internet Page “Products”: http://www.infineon.com/products.Dimensions in mm

Datasheet 29 Rev. 1.0, 2009-05-05

Smart Low Side Power Switch

HITFET - BTS 3256D

Revision History

11 Revision History

Version Date Changes

Rev. 1.0 2009-05-05 released Datasheet

Edition 2009-05-05

Published by

Infineon Technologies AG

81726 Munich, Germany

Legal Disclaimer

The information given in this document shall in no event be regarded as a guarantee of conditions or

characteristics (“Beschaffenheitsgarantie”). With respect to any examples or hints given herein, any typical values

stated herein and/or any information regarding the application of the device, Infineon Technologies hereby

disclaims any and all warranties and liabilities of any kind, including without limitation warranties of

non-infringement of intellectual property rights of any third party.

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For further information on technology, delivery terms and conditions and prices please contact your nearest

Infineon Technologies Office (www.infineon.com).

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Due to technical requirements components may contain dangerous substances. For information on the types in

question please contact your nearest Infineon Technologies Office.

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